<?php
namespace lib;
class WeChatFx
{
  private $appId; 
  private $appSecret; 
 
  public function __construct($appId, $appSecret) { 
    $this->appId = $appId; 
    $this->appSecret = $appSecret; 
  } 
 
  public function getSignPackage() { 
    $jsapiTicket = $this->getJsApiTicket(); 
 
    // 注意 URL 一定要动态获取，不能 hardcode. 
    $protocol = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off' || $_SERVER['SERVER_PORT'] == 443) ? "https://" : "http://"; 
    $url = "$protocol$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]"; 
 
    $timestamp = time(); 
    $nonceStr = $this->createNonceStr(); 
 
    // 这里参数的顺序要按照 key 值 ASCII 码升序排序 
    $string = "jsapi_ticket=$jsapiTicket&noncestr=$nonceStr×tamp=$timestamp&url=$url"; 
 
    $signature = sha1($string); 
 
    $signPackage = array( 
      "appId"     => $this->appId, 
      "nonceStr"  => $nonceStr, 
      "timestamp" => $timestamp, 
      "url"       => $url, 
      "signature" => $signature, 
      "rawString" => $string 
    ); 
    return $signPackage;  
  } 
 
  private function createNonceStr($length = 16) { 
    $chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; 
    $str = ""; 
    for ($i = 0; $i < $length; $i++) { 
      $str .= substr($chars, mt_rand(0, strlen($chars) - 1), 1); 
    } 
    return $str; 
  } 
 
  private function getJsApiTicket() { 
    // jsapi_ticket 应该全局存储与更新，以下代码以写入到文件中做示例 
    $data = json_decode($this->get_php_file("jsapi_ticket.php")); 
    if ($data->expire_time < time()) { 
      $accessToken = $this->getAccessToken(); 
      // 如果是企业号用以下 URL 获取 ticket 
      // $url = "https://qyapi.weixin.qq.com/cgi-bin/get_jsapi_ticket?access_token=$accessToken"; 
      $url = "https://api.weixin.qq.com/cgi-bin/ticket/getticket?type=jsapi&access_token=$accessToken"; 
      $res = json_decode($this->httpGet($url)); 
      $ticket = $res->ticket; 
      if ($ticket) { 
        $data->expire_time = time() + 7000; 
        $data->jsapi_ticket = $ticket; 
        $this->set_php_file("jsapi_ticket.php", json_encode($data)); 
      } 
    } else { 
      $ticket = $data->jsapi_ticket; 
    } 
 
    return $ticket; 
  } 
 
  private function getAccessToken() { 
    // access_token 应该全局存储与更新，以下代码以写入到文件中做示例 
    $data = json_decode($this->get_php_file("access_token.php")); 
    if ($data->expire_time < time()) { 
      // 如果是企业号用以下URL获取access_token 
      // $url = "https://qyapi.weixin.qq.com/cgi-bin/gettoken?corpid=$this->appId&corpsecret=$this->appSecret"; 
      $url = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=$this->appId&secret=$this->appSecret"; 
      $res = json_decode($this->httpGet($url)); 
      $access_token = $res->access_token; 
      if ($access_token) { 
        $data->expire_time = time() + 7000; 
        $data->access_token = $access_token; 
        $this->set_php_file("access_token.php", json_encode($data)); 
      } 
    } else { 
      $access_token = $data->access_token; 
    } 
    return $access_token; 
  } 
 
  private function httpGet($url) { 
    $curl = curl_init(); 
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, true); 
    curl_setopt($curl, CURLOPT_TIMEOUT, 500); 
    // 为保证第三方服务器与微信服务器之间数据传输的安全性，所有微信接口采用https方式调用，必须使用下面2行代码打开ssl安全校验。 
    // 如果在部署过程中代码在此处验证失败，请到 http://curl.haxx.se/ca/cacert.pem 下载新的证书判别文件。 
    curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, true); 
    curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, true); 
    curl_setopt($curl, CURLOPT_URL, $url); 
 
    $res = curl_exec($curl); 
    curl_close($curl); 
 
    return $res; 
  } 
 
  private function get_php_file($filename) { 
    return trim(substr(file_get_contents($filename), 15)); 
  } 
  private function set_php_file($filename, $content) { 
    $fp = fopen($filename, "w"); 
    fwrite($fp, "<?php exit();?>" . $content); 
    fclose($fp); 
  }
 }
